[docker] Ubuntu docker build failing

[podhrmic]

Unclear what is causing the problem, building the image on my local machine works fine. We still need to resolve this.
A sample error log: https://github.com/rems-project/cerberus/actions/runs/13314671129/job/37185654852

It appears that the RedHat build is working, so the culprit might be the Github action rather than anything in the Dockerfile itself. And indeed it looks like it is - see docker/setup-qemu-action#198

The fix is to switch to docker/[email protected] (see e.g. this PR)